Guess who I found when I was recovering my gear? The High Overseer. I had left him alive and then here he was, turned into a weeper. I thought that was awesome

I saw him too, wasn't quite sure if it was him, did he have the brand?

Yep. I snuck up on the weeper, then choked him out. As he fell, I noticed a mark on his face and went - "Wait a minute..." I flipped the body back over and it was indeed the High Overseer! Nearby you can find a note written by him as he is losing his mind, in which he places a curse on Corvo with his last sane moments.